Patent GB-471528-A (GB)
Title: Improvements in or relating to method and apparatus for welding
IPC: F04D25/10
Filed: 1936-03-04
Abstract: 471,528. Making longitudinally welded tubes &c. SPANG, CHALFANT, & CO., Inc. March 4, 1936, No. 6548. Convention date, March 25, 1935. [Classes 83 (ii) and 83 (iv)] In making longitudinally welded tubes &c. sheet blanks are supplied to a receiving table 15, Fig. 1a, from which they are fed past edge-trimming tools 17 and a cleaner 18 to a bending press 20. The bent skelps pass by conveying rollers 46 to a chain conveyer 52, Fig. 1b, which passes them through sizing and forming rolls 26-29 and then to positive rack feeding bars 65, 66, each of which feeds alternate skelps to aligning rolls 115, Fig. 1c, and then forces them at a uniform speed through the welding machine 111. The welded tubes are then received by withdrawing and sizing rolls 145. Most of the rolls are mounted in similar standards 11 which are adjustable along rails 10 passing along the machine but made discontinuous for the reception of such units as the bending and welding machines 20, 111. The blanks are fed by power or other means to the edge trimmer 17, which may provide any desired type of edge on the plates, and thence to the cleaner 18 which may be a centrifugal sand blasting machine. A power driven conveyer 19 then passes the sheets to the bending machine 20 which applies pressure to the whole length of each sheet to form it into a tubular blank of elliptical cross-section in one or more steps. The partly formed skelps are positively ejected from the bending machine and are transferred by rollers 46, alternate rollers being driven by electric motors 47, to a chain conveyer 52 passing over sprockets on the spindles of further rollers 46 and driven by a motor 54 through gearing 55. Dogs 53 on the chain engagebehind a skelp and force it between rolls 40 which partly close the elliptical section and then between rolls 26 ... 29 which substantially encircle the skelp and reduce it to approximately circular section. These rolls, with the exception of the bottom roll 27, are positively driven by motors 31 and gearing 30, and a mandrel 35 carrying internal rollers 36 supports the skelp at the seam and the opposite side. The upper roll 28 has a fin 38 engaging the open seam to align the skelp. Welding.-The formed skelps are forced through the welding machine at a uniform rate to produce uniformity of the weld by means of two racks 65, 66 which are reciprocated in opposite directions by oppositely running worms 71, Fig. 7, driven by a motor 73 and gearing 74, Fig. 1b. Each rack carries a dog 76 engaging a switch 75 or 77 at the rearward end of its stroke to reverse the motor, one rack feeding a skelp forwards whilst the other is returning. The motor may be controlled by push button switches actuated by an operator at the welding machine so as to synchronize the reciprocations of the racks with the supply of skelps. Each rack carries a dog 84 at the forward end to engage behind a skelp T, the dogs being pivoted and pressed upwards by spring plungers 86 and being laterally movable against springs 90 to allow them to clear the other dog and skelp during the idle return movement. The racks are supported by rollers 68, Fig. 11. The skelps are also fed frictionally by upper rolls 61 having fins engaging the seam and are supported by narrow side and lower rolls which are arranged to clear the racks, alternate rolls 61 being driven by motors 62, so as to tend to feed the skelps at a slightly lower speed than the racks. For adjusting the strokes of the racks, removable couplings 79 are provided in the drives to the worms 71. Before entering the welding throat the skelps pass through aligning and re-forming rolls 115, 119, Fig. 11, the former having fins 116, which are not positively driven and which contact the skelp over about 120‹ of its circumference. The welding throat is formed by electrode rollers 130, side rolls 131 and a bottom roll 132 which substantially encircle the pipe and produce a heavy diameter-reducing pressure which upsets the metal on each side of the seam to produce a " body weld," as distinct from a surface weld of the " stitched " or " pasted " kind. Further side rolls 133, 134 close the seam before and after welding and a roll 135 keeps the seam open till the proper time. The electrodes 130 are trimmed by a cutter 136 and a flash cutter 137 for the welded seam is provided. The welded tube is planished by rolls 138, 140 and a mandrel 139. The dogs 84 push the pipes to within a few inches of the end, after which the pipes are drawn through by final sizing rolls 145 Fig. 1c, driven by motors 146, which completely encircle the pipes. Alternatively the pipes may be withdrawn by pick-up tongs or friction means.